Murata Minako, Yudo Kazuo, Nakamura Hiroshi, Chiba Junji, Okamoto Kazuki, Suematsu Naoya, Nishioka Kusuki, Beppu Moroe, Inoue Kazuhiko, Kato Tomohiro, Masuko Kayo
Department of Frontier Medicine, Institute of Medical Science, St. Marianna University School of Medicine, Kawasaki, Japan.
J Orthop Res. 2009 Jan;27(1):50-7. doi: 10.1002/jor.20703.
The objective of this article was to investigate the role and expression of a novel adipocytokine, angiopoietin-like-4 (ANGPTL4), in arthropathy. Human chondrocytes were obtained from articular cartilage of patients with rheumatoid arthritis (RA) and osteoarthritis (OA), who underwent total knee or hip arthroplasty. Isolated chondrocytes were cultured under hypoxic (95% N(2), 5% CO(2)) or normoxic conditions. The effects of hypoxia on ANGPTL4 expression were determined by real-time reverse transcription polymerase chain reaction and Western blot analysis. We examined the role of ANGPTL4 using small interference RNA or by stimulating chondrocytes with recombinant ANGPTL4 protein. ANGPTL4 expression in the articular cartilage specimens was examined by immunohistochemistry. Hypoxia induced a significant increase in ANGPTL4 production (p < 0.05). Incubation of chondrocytes in vitro with recombinant ANGPTL4 enhanced the expression of matrix metalloproteinase (MMP)-1 and MMP-3. Downregulation of ANGPTL4 mRNA expression by siRNA diminished the expression of MMP-1, but not that of MMP-3, suggesting that each proteinase has a distinct response to ANGPTL4. Although the in vitro responses of chondrocytes to hypoxia were similar between RA and OA samples, the in vivo expression of ANGPTL4 had unique disease-specific patterns, suggesting differences in oxygen tension in vivo. Human chondrocytes expressed ANGPTL4 and the expression was enhanced by hypoxia. ANGPTL4 might modulate cartilage metabolism by regulating MMPs.
本文的目的是研究一种新型脂肪细胞因子血管生成素样4（ANGPTL4）在关节病中的作用和表达。从接受全膝关节或髋关节置换术的类风湿关节炎（RA）和骨关节炎（OA）患者的关节软骨中获取人软骨细胞。将分离的软骨细胞在低氧（95% N₂，5% CO₂）或常氧条件下培养。通过实时逆转录聚合酶链反应和蛋白质印迹分析确定低氧对ANGPTL4表达的影响。我们使用小干扰RNA或用重组ANGPTL4蛋白刺激软骨细胞来研究ANGPTL4的作用。通过免疫组织化学检查ANGPTL4在关节软骨标本中的表达。低氧诱导ANGPTL4产生显著增加（p < 0.05）。用重组ANGPTL4体外培养软骨细胞可增强基质金属蛋白酶（MMP）-1和MMP-3的表达。小干扰RNA下调ANGPTL4 mRNA表达可减少MMP-1的表达，但不影响MMP-3的表达，这表明每种蛋白酶对ANGPTL4有不同的反应。尽管RA和OA样本中软骨细胞对低氧的体外反应相似，但ANGPTL4的体内表达具有独特的疾病特异性模式，提示体内氧张力存在差异。人软骨细胞表达ANGPTL4，低氧可增强其表达。ANGPTL4可能通过调节基质金属蛋白酶来调节软骨代谢。
